package com.itheima.utils;

import java.text.SimpleDateFormat;
import java.util.*;

/**
 * 日期操作工具类
 */
public class DateUtils {
   /**
    * 日期转换-  String -> Date
    *
    * @param dateString 字符串时间
    * @return Date类型信息
    * @throws Exception 抛出异常
    */
   public static Date parseString2Date(String dateString) throws Exception {
      if (dateString == null) {
         return null;
      }
      return parseString2Date(dateString, "yyyy-MM-dd");
   }

   /**
    * 日期转换-  String -> Date
    *
    * @param dateString 字符串时间
    * @param pattern    格式模板
    * @return Date类型信息
    * @throws Exception 抛出异常
    */
   public static Date parseString2Date(String dateString, String pattern) throws Exception {
      if (dateString == null) {
         return null;
      }
      SimpleDateFormat sdf = new SimpleDateFormat(pattern);
      Date date = sdf.parse(dateString);
      return date;
   }

   /**
    * 日期转换 Date -> String
    *
    * @param date Date类型信息
    * @return 字符串时间
    * @throws Exception 抛出异常
    */
   public static String parseDate2String(Date date) throws Exception {
      if (date == null) {
         return null;
      }
      return parseDate2String(date, "yyyy-MM-dd");
   }

   /**
    * 日期转换 Date -> String
    *
    * @param date    Date类型信息
    * @param pattern 格式模板
    * @return 字符串时间
    * @throws Exception 抛出异常
    */
   public static String parseDate2String(Date date, String pattern) throws Exception {
      if (date == null) {
         return null;
      }
      SimpleDateFormat sdf = new SimpleDateFormat(pattern);
      String strDate = sdf.format(date);
      return strDate;
   }

   /**
    * 获取当前日期的本周一是几号
    *
    * @return 本周一的日期
    */
   public static Date getThisWeekMonday() {
      Calendar cal = Calendar.getInstance();
      cal.setTime(new Date());
      // 获得当前日期是一个星期的第几天
      int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
      if (1 == dayWeek) {
         cal.add(Calendar.DAY_OF_MONTH, -1);
      }
      // 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
      cal.setFirstDayOfWeek(Calendar.MONDAY);
      // 获得当前日期是一个星期的第几天
      int day = cal.get(Calendar.DAY_OF_WEEK);
      // 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
      cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
      return cal.getTime();
   }

   /**
    * 获取当前日期周的最后一天
    *
    * @return 当前日期周的最后一天
    */
   public static Date getSundayOfThisWeek() {
      Calendar c = Calendar.getInstance();
      int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - 1;
      if (dayOfWeek == 0) {
         dayOfWeek = 7;
      }
      c.add(Calendar.DATE, -dayOfWeek + 7);
      return c.getTime();
   }

   /**
    * 根据日期区间获取月份列表
    *
    * @param minDate 开始时间
    * @param maxDate 结束时间
    * @return 月份列表
    * @throws Exception
    */
   public static List<String> getMonthBetween(String minDate, String maxDate, String format) throws Exception {
      ArrayList<String> result = new ArrayList<>();
      SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");

      Calendar min = Calendar.getInstance();
      Calendar max = Calendar.getInstance();

      min.setTime(sdf.parse(minDate));
      min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);

      max.setTime(sdf.parse(maxDate));
      max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);
      SimpleDateFormat sdf2 = new SimpleDateFormat(format);

      Calendar curr = min;
      while (curr.before(max)) {
         result.add(sdf2.format(curr.getTime()));
         curr.add(Calendar.MONTH, 1);
      }

      return result;
   }

   /**
    * 根据日期获取年度中的周索引
    *
    * @param date 日期
    * @return 周索引
    * @throws Exception
    */
   public static Integer getWeekOfYear(String date) throws Exception {
      Date useDate = parseString2Date(date);
      Calendar cal = Calendar.getInstance();
      cal.setTime(useDate);
      return cal.get(Calendar.WEEK_OF_YEAR);
   }

   /**
    * 根据年份获取年中周列表
    *
    * @param year 年分
    * @return 周列表
    * @throws Exception
    */
   public static Map<Integer, String> getWeeksOfYear(String year) throws Exception {
      Date useDate = parseString2Date(year, "yyyy");
      Calendar cal = Calendar.getInstance();
      cal.setTime(useDate);
      //获取年中周数量
      int weeksCount = cal.getWeeksInWeekYear();
      Map<Integer, String> mapWeeks = new HashMap<>(55);
      for (int i = 0; i < weeksCount; i++) {
         cal.get(Calendar.DAY_OF_YEAR);
         mapWeeks.put(i + 1, parseDate2String(getFirstDayOfWeek(cal.get(Calendar.YEAR), i)));
      }
      return mapWeeks;
   }

   /**
    * 获取某年的第几周的开始日期
    *
    * @param year 年分
    * @param week 周索引
    * @return 开始日期
    * @throws Exception
    */
   public static Date getFirstDayOfWeek(int year, int week) throws Exception {
      Calendar c = new GregorianCalendar();
      c.set(Calendar.YEAR, year);
      c.set(Calendar.MONTH, Calendar.JANUARY);
      c.set(Calendar.DATE, 1);

      Calendar cal = (GregorianCalendar) c.clone();
      cal.add(Calendar.DATE, week * 7);

      return getFirstDayOfWeek(cal.getTime());
   }

   /**
    * 获取某年的第几周的结束日期
    *
    * @param year 年份
    * @param week 周索引
    * @return 结束日期
    * @throws Exception
    */
   public static Date getLastDayOfWeek(int year, int week) throws Exception {
      Calendar c = new GregorianCalendar();
      c.set(Calendar.YEAR, year);
      c.set(Calendar.MONTH, Calendar.JANUARY);
      c.set(Calendar.DATE, 1);

      Calendar cal = (GregorianCalendar) c.clone();
      cal.add(Calendar.DATE, week * 7);

      return getLastDayOfWeek(cal.getTime());
   }

   /**
    * 获取本月最后一天日期
    * @return
    */
   public static Date getLastDayOfMonth() throws Exception {
      Calendar cal = Calendar.getInstance();//获取当天日期对象
      cal.add(Calendar.MONTH, 1);//翻到下一个月
      cal.set(Calendar.DAY_OF_MONTH,1);//指向下个月第一天

      return cal.getTime();
   }

   /**
    * 获得指定月份的最后一天
    * @param currentDate
    * @return
    * @throws Exception
    */
   public static Date getLastDayOfMonth(Date currentDate) throws Exception {
      Calendar cal = Calendar.getInstance();//获取当天日期对象
      cal.setTime(currentDate);
      cal.add(Calendar.MONTH, 1);//翻到下一个月
      cal.set(Calendar.DAY_OF_MONTH,1);//指向下个月第一天

      return cal.getTime();
   }


   /**
    * 获取当前时间所在周的开始日期
    *
    * @param date 当前时间
    * @return 开始时间
    */
   public static Date getFirstDayOfWeek(Date date) {
      Calendar c = new GregorianCalendar();
      c.setFirstDayOfWeek(Calendar.SUNDAY);
      c.setTime(date);
      c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek());
      return c.getTime();
   }

   /**
    * 获取当前时间所在周的结束日期
    *
    * @param date 当前时间
    * @return 结束日期
    */
   public static Date getLastDayOfWeek(Date date) {
      Calendar c = new GregorianCalendar();
      c.setFirstDayOfWeek(Calendar.SUNDAY);
      c.setTime(date);
      c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6);
      return c.getTime();
   }

   //获得上周一的日期
   public static Date geLastWeekMonday(Date date) {
      Calendar cal = Calendar.getInstance();
      cal.setTime(getThisWeekMonday(date));
      cal.add(Calendar.DATE, -7);
      return cal.getTime();
   }

   //获得本周一的日期
   public static Date getThisWeekMonday(Date date) {
      Calendar cal = Calendar.getInstance();
      cal.setTime(date);
      // 获得当前日期是一个星期的第几天
      int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
      if (1 == dayWeek) {
         cal.add(Calendar.DAY_OF_MONTH, -1);
      }
      // 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
      cal.setFirstDayOfWeek(Calendar.MONDAY);
      // 获得当前日期是一个星期的第几天
      int day = cal.get(Calendar.DAY_OF_WEEK);
      // 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
      cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
      return cal.getTime();
   }

   //获得下周一的日期
   public static Date getNextWeekMonday(Date date) {
      Calendar cal = Calendar.getInstance();
      cal.setTime(getThisWeekMonday(date));
      cal.add(Calendar.DATE, 7);
      return cal.getTime();
   }

   //获得今天日期
   public static Date getToday() {
      return new Date();
   }

   //获得本月一日的日期
   public static Date getFirstDay4ThisMonth() {
      Calendar calendar = Calendar.getInstance();
      calendar.set(Calendar.DAY_OF_MONTH, 1);
      return calendar.getTime();
   }

   //获得指定月份的1号日期
   public static Date getFirstDay4ThisMonth(Date currentDate) {
      Calendar calendar = Calendar.getInstance();
      calendar.setTime(currentDate);
      calendar.set(Calendar.DAY_OF_MONTH, 1);
      return calendar.getTime();
   }

   //获取本月第n天的日期
   public static Date getNDayOfThisMonth(Integer n) {
      //获取当前日期
      Calendar calendar = Calendar.getInstance();
      //获取当前日期是本月第几天
      int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
      //调整到第n天的日期
      calendar.add(Calendar.DATE, n - dayOfMonth);
      return calendar.getTime();
   }

   //获取本周第n天的日期,n可取[1-7]
   public static Date getNDayOfThisWeek(Integer n) throws RuntimeException {
      if (n < 1 || n > 7) {
         throw new RuntimeException("日期输入有误,必须为[1-7]之间");
      }
      //当前日期
      Calendar calendar = Calendar.getInstance();
      //获取今天是本周的第几天(周日是1-周六7)
      int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
      if (dayOfWeek == 1) {//改为中国的算法周一是1,周日是7
         dayOfWeek = 7;
      } else {
         dayOfWeek = dayOfWeek - 1;
      }
      //调整到周n
      calendar.add(Calendar.DATE, n - dayOfWeek);

      return calendar.getTime();
   }

   public static void main(String[] args) {
      try {
         System.out.println("本周一" + parseDate2String(getThisWeekMonday()));
         System.out.println("本月一日" + parseDate2String(getFirstDay4ThisMonth()));
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}
